The invention relates to improvements in methods of and in apparatus for ascertaining the characteristics of sections of photographic material, and more particularly to improvements in methods of and in apparatus for ascertaining the characteristics of shorter and longer sections of exposed and developed photographic films. Still more particularly, the invention relates to improvements in methods and apparatus which can be resorted to with advantage to ascertain the density of shorter and longer sections of photographic material, for example, (a) the density of successive frames forming part of strips or webs of coherent frames or (b) the density of discrete frames.
Commonly owned U.S. Pat. No. 4,627,719 (granted Dec. 9, 1986 to Nitsch et al. for "Method of and apparatus for reproducing the images of film frames") discloses a method of and an apparatus for ascertaining the density of running webs of exposed and developed photographic films. The films are advanced in a first direction along a predetermined path through a monitoring station to be scanned by a system of photocells which generate signals for storage in the memory of a microprocessor. Such signals are utilized to properly image the frames of the respective films onto photographic paper while the films are moved along the same path but in a second direction counter to the first direction. A pivotable mirror is provided at the monitoring station to intercept light passing through successive increments of a film which is being advanced in the first direction, and the intercepted light is directed toward the photocells so that the photocells can transmit appropriate signals to the microprocessor. The mirror is pivoted out of the way preparatory to copying so that light which passes through the frames during advancement of the film in the second direction and is modified in accordance with the respective signals can impinge upon successive increments of a running strip of photographic paper.
The method and apparatus of Nitsch et al. are quite satisfactory in connection with the monitoring and copying of relatively long sections of photographic material, i.e., one or more elongated customer films each of which comprises a long series or file of exposed and developed film frames with customary frame lines between neighboring film frames. However, the patented method and aparatus are less suited for monitoring and copying of relatively short sections of photographic material, e.g., of discrete film frames. The length of sections which can be monitored and copied in the patented apparatus is determined by the distance between the film advancing devices upstream and downstream of the monitoring station (which constitutes the copying station during advancement of a film in the second direction). The aforementioned distance exceeds the length of a single film frame; therefore, if a single film frame is to be monitored and copied, it must be provided with an extension in the form of a strip or tongue extending from and serving to permit introduction of the film frame into the patented apparatus. The necessity to provide the individual or discrete film frames with extensions contributes significantly to the cost of the copying operation, not only because the extensions must be separately produced and affixed to discrete film frames but also because the periods of time which are required for the monitoring and copying of a discrete film frame are too long.